A DPOAE test is a method used to assess the function of the outer hair cells in the inner ear by measuring specific acoustic signals.
Understanding DPOAE
What are Distortion Product Otoacoustic Emissions (DPOAE)?
Distortion Product Otoacoustic Emissions, or DPOAEs, are sounds produced by the inner ear. Specifically, these are acoustic signals that can be detected in the ear canal after the ear is stimulated with two pure tones.
- The ear is stimulated with two pure tones at different frequencies, labeled f1 and f2.
- These tones are typically presented at a specific ratio; the reference mentions a ratio of f2/f1 of 1.22.
How DPOAE Testing Works
The test involves presenting two tones into the ear canal. If the outer hair cells are functioning correctly, they generate a faint sound in response. This response sound, the DPOAE, is measured by a sensitive microphone placed in the ear canal.
Why are DPOAE Tests Useful?
- Assess Outer Hair Cell Function: DPOAE tests are a reliable method for evaluating the health and function of the outer hair cells.
- Hearing Screening: DPOAEs are particularly useful in newborn hearing screenings because they are non-invasive and can quickly and accurately detect certain types of hearing loss.
- Monitoring Ototoxicity: These tests can monitor the effect of medications that may damage the inner ear.
- Early Detection: They help to detect subtle changes in hearing, often before they are noticeable through standard hearing tests.
Practical Insights
- A normal DPOAE response usually indicates healthy outer hair cells.
- Absent or reduced DPOAEs can suggest issues such as outer hair cell damage, which is a common cause of sensorineural hearing loss.
- DPOAE tests are typically not influenced by the middle ear.
Summarized Information
| Feature | Description |
|---|---|
| What it measures | Acoustic signals from outer hair cells |
| Stimuli | Two pure tones at frequencies f1 and f2 (f2/f1 ratio typically 1.22) |
| Detection | Measured in the ear canal with a microphone |
| Indication | Normal response indicates healthy outer hair cell function; abnormal response might suggest outer hair cell issues. |
| Key Use Cases | Newborn hearing screening, monitoring for ototoxicity, early detection of hearing loss |
